BACKGROUNDIn 4 clinical studies of a biological tissue isolate (BTI) similar to Rellidep, the majority of subjects reported improved well-being and mood. Based on these reports of positive effect on mood in trials, an antidepressant pilot study was undertaken with the BTI Rellidep.METHODTwenty-three subjects (14 women and 9 men; mean age, 44.8 years) with major depressive disorder entered an 8-week trial of Rellidep with a 17-item Hamilton Depression Rating Scale (HAM-D) score of 18 or above. Three subjects dropped out before beginning treatment, leaving an intention-to-treat (ITT) sample of 20. Sixteen subjects completed the trial. All patients received Rellidep 1000 mg (500 mg × 2) twice a day orally daily for 8 weeks. No other treatments were permitted except for intermittent lorazepam for sleep if necessary. The primary response to treatment outcome was a 50% decline on the HAM-D. Secondary measures included the Beck Depression Inventory, Montgomery-Åsberg Depression Rating Scale, Clinical Global Impression, Hamilton Rating Scale for Anxiety, Medical Outcomes Study Short-Form 36, and Arizona Sexual Experience Scale.RESULTSThe overall response rate was 75% (15/20). Almost 87% of those who responded did so by week 4. The data analysis of change scores indicates that for the ITT population the decrease in the HAM-D was statistically significant (P < 0.001). On all other measures, improvement from baseline was statistically significant (P < 0.001), except for the Arizona Sexual Experience Scale (ITT: P = 0.055). There were no significant adverse events.CONCLUSIONSThe positive outcome of this open trial indicates that Rellidep may be an effective and safe antidepressant. Further placebo-controlled trials are indicated.