Background Mixed depression is a common, dimensional phenomenon that is increasingly recognized in unipolar and bipolar disorders. We piloted a modified version of the Hypomania Checklist (mHCL-32) to assess the prevalence and clinical correlates of concurrent manic (hypo) symptoms in depressed patients. Methods The mHCL-32, Young Mania Rating Scale (YMRS) and Hamilton Rating Scale for Depression (HAMD-24) were utilized in the assessment of unipolar (UP=61) and bipolar (BP=44) patients with an index major depressive episode confirmed by the Structured Clinical Interview for DSM-IV (SCID). Differential mHLC-32 item endorsement was compared between UP and BP. Correlation analyses assessed the association of symptom dimensions measured by mHCL-32, YMRS and HAMD-24. Results There was no significant difference between mood groups in the mean mHCL-32 and YMRS scores. Individual mHLC-32 items of increased libido, quarrels, and caffeine intake were endorsed more in BP vs. UP patients. The mHCL-32 active-elevated subscale score was positively correlated with the YMRS in BP patients and negatively correlated with HAMD-24 in UP patients. Conversely, the mHCL-32 irritable-risk taking subscale score was positively correlated with HAMD-24 in BP and with YMRS in UP patients. Limitations Small sample size and cross-sectional design. Conclusion Modifying the HCL to screen for (hypo) manic symptoms in major depression may have utility in identifying mixed symptoms in both bipolar vs. unipolar depression. Further research is encouraged to quantify mixed symptoms with standardized assessments.