LC-MS/MS methods for the quantification of morphine, morphine-3-glucuronide, morphine-6-glucuronide, codeine, 6-acetylmorphine, cocaine, benzoylecgonine, ecgonine methyl ester, hydroxybenzoylecgonine, cocaethylene, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), methadone, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine in human placenta and umbilical cord were developed and validated. Specimens (1 ± 0.02 g) were homogenized with the Ultra-Turrax T8 disperser and centrifuged, and the supernatant was submitted to solid-phase extraction with Oasis MCX cartridges. Chromatographic separation was performed using an Atlantis T3 analytical column (100 × 2.1 mm, 3 μm) and a gradient of 0.1 % formic acid and acetonitrile. Selectivity was verified in 10 different blank specimens. The method was linear from 1-5 to 100-500 ng/g, depending on the analyte. Limits of detection and quantification ranged from 0.5 to 2.5 ng/g and 1 to 5 ng/g, respectively. Method imprecision was ≤15.3 %, except for MDMA at low quality control (18.1 %); accuracy, 87.1 to 114 %; extraction efficiency, 16.3 to 154.0 % (%CV = 1.8-39.4 %); matrix effect, -75.7 to 449.9 % (%CV = 3.5-50 %); and process efficiency, 8.7 to 316.0 %. The method was applied to authentic placenta and umbilical cord specimens from drug-user pregnant women.