Three hundred thirteen patients with signs of depression or spontaneous or evoked pain of coccygeal area were studied over six months. One hundred eighty (58 percent) had no spontaneous pain, 87 (28 percent) had moderate pain, and 46 (15 percent) a severe coccygodynia leading to consultation. In four of the latter group, no other sign of depression was found. Seventy-nine percent of the patients with spontaneous pain and 66 percent without spontaneous pain had coccygeal pain evoked by rectal digital examination (RDE). Seventy-one percent of the patients with spontaneous pain and 56 percent without spontaneous pain had paracoccygeal pain evoked by RDE. Among severely depressed patients (Group III), 76 percent had an evoked pain and 80 percent a coccygeal pain--either spontaneous or evoked. In 178 (57 percent), all signs disappeared when treated with various antidepressants in seven visits and within six months. Seven (2 percent) were failures; 44 (14 percent) were lost during follow-up; 84 (27 percent) did not return after the first consultation. After treatment in five patients was stopped, all signs recurred together and disappeared when adapted treatment was administered again. In 120 consecutive patients who had colonic roentgenologic examination and no depressive sign, two had coccygeal and muscular pain at rectal touch. A highly significant correlation was found between the following parameters: evoked pain and depressive status in noncoccygodynic patients, coccygodynia and evoked pain, coccygeal and paracoccygeal muscular pain. Severity of coccygodynia was not correlated with the number of depressive signs. Sex, age, and treatment efficiency were not correlated. The mechanism of depressive pain is discussed. RDE-evoked pain is proposed as an "objective" diagnostic sign for masked depression and as a means of evolution control. The frequency of the disease and efficiency of treatment are stressed.