diff --git a/http/src/main/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamException.scala b/http/src/main/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamException.scala
index bb38dc82a3..b2c91fde5d 100644
--- a/http/src/main/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamException.scala
+++ b/http/src/main/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamException.scala
@@ -1,9 +1,13 @@
 package org.broadinstitute.dsde.workbench.leonardo.dao.sam
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import org.broadinstitute.dsde.workbench.client.sam.ApiException
+import org.broadinstitute.dsde.workbench.client.sam.model.ErrorReport
 import org.broadinstitute.dsde.workbench.leonardo.model.LeoException
 import org.broadinstitute.dsde.workbench.model.TraceId
 
+import scala.util.Try
+
 /**
  * Represents an exception interacting with Sam.
  */
@@ -16,13 +20,38 @@ class SamException private (message: String, code: Int, cause: Throwable, traceI
     )
 
 object SamException {
+  val objectMapper = new ObjectMapper
+
   def create(messagePrefix: String, apiException: ApiException, traceId: TraceId): SamException =
     new SamException(
       // TODO: investigate whether we need to extract the ApiException message like in
       //  TCL SamExceptionFactory
-      s"$messagePrefix: ${apiException}",
+      extractMessage(messagePrefix, apiException),
       apiException.getCode,
       apiException.getCause,
       traceId
     )
+
+  /**
+   * Extracts a useful message from a Sam client ApiException.
+   *
+   * Logic borrowed from terra-common-lib SamExceptionFactory class. We can't use the class directly
+   * because it has Spring dependencies, which Leo excludes.
+   */
+  private def extractMessage(messagePrefix: String, apiException: ApiException): String = {
+    // The generated ApiException class unfortunately formats getMessage(), and includes
+    // the entire response body. We want to extract the actual message from that.
+    val messagePattern = "^Message: ([\\S\\s]*)\\nHTTP response code:".r
+    val extractedMessage = messagePattern.findFirstMatchIn(apiException.getMessage).map(_.group(1)).filterNot(_.isBlank)
+
+    // If we could not extract the top-level message, try to deserialize the error report
+    // buried one level down and extract the message from that.
+    val finalMessage = extractedMessage.orElse {
+      val errorReport = Try(objectMapper.readValue(apiException.getResponseBody, classOf[ErrorReport]))
+      errorReport.map(_.getMessage).toOption
+    }
+
+    // Prepend the message prefix to the extracted message, if we have one.
+    s"$messagePrefix: ${finalMessage.getOrElse("")}"
+  }
 }
diff --git a/http/src/test/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamExceptionSpec.scala b/http/src/test/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamExceptionSpec.scala
new file mode 100644
index 0000000000..d0f00d7388
--- /dev/null
+++ b/http/src/test/scala/org/broadinstitute/dsde/workbench/leonardo/dao/sam/SamExceptionSpec.scala
@@ -0,0 +1,49 @@
+package org.broadinstitute.dsde.workbench.leonardo.dao.sam
+
+import akka.http.scaladsl.model.StatusCodes
+import com.fasterxml.jackson.databind.ObjectMapper
+import org.broadinstitute.dsde.workbench.client.sam.ApiException
+import org.broadinstitute.dsde.workbench.client.sam.model.ErrorReport
+import org.broadinstitute.dsde.workbench.leonardo.LeonardoTestSuite
+import org.broadinstitute.dsde.workbench.model.TraceId
+import org.scalatest.flatspec.AnyFlatSpec
+
+import scala.jdk.CollectionConverters._
+
+class SamExceptionSpec extends AnyFlatSpec with LeonardoTestSuite {
+  val objectMapper = new ObjectMapper
+
+  "SamException" should "create from an ApiException" in {
+    val cause = new RuntimeException("cause")
+    val errorReport = new ErrorReport().statusCode(400).message("error report message")
+    val apiException = new ApiException(
+      "test message",
+      cause,
+      400,
+      Map("responseHeader1" -> List("responseHeader1Value").asJava).asJava,
+      objectMapper.writeValueAsString(errorReport)
+    )
+    val samException = SamException.create("messagePrefix", apiException, TraceId("traceId"))
+
+    samException.message shouldBe "messagePrefix: test message"
+    samException.statusCode shouldBe StatusCodes.BadRequest
+    samException.cause shouldBe cause
+  }
+
+  it should "extract the message from the ErrorReport if the top-level message is blank" in {
+    val cause = new RuntimeException("cause")
+    val errorReport = new ErrorReport().statusCode(400).message("error report message")
+    val apiException = new ApiException(
+      "",
+      cause,
+      400,
+      Map("responseHeader1" -> List("responseHeader1Value").asJava).asJava,
+      objectMapper.writeValueAsString(errorReport)
+    )
+    val samException = SamException.create("messagePrefix", apiException, TraceId("traceId"))
+
+    samException.message shouldBe "messagePrefix: error report message"
+    samException.statusCode shouldBe StatusCodes.BadRequest
+    samException.cause shouldBe cause
+  }
+}