The goniometric, optical and x-ray data obtained from the crystallographic study of crystals of lead diethyldithiocarbamate are reported. System: monoclinic. Class: m. 1.4098 : 1 : 0.7972, $\beta$ = 117° 41'. Refractive indices: $\alpha_{D}$ = 1.782, $\beta_{D}$ = 1.825, $\gamma_{D}$ = 1.923. No experimentally detectable optical power. Very strong piezoelectricity. Space group: Cc, 16.58 Å, 11.78 Å, 9.36 Å, $\beta$ = 117° 37'. The structural data reported in Bibliography [4] are to be regarded as mistaken.