The physicochemical properties and application of phenoplasts and aminoplasts are reviewed. Phenoplasts and aminoplasts are polycondensation resins; the condensation/equilibrium reaction may be stopped at any desired moment. Semicured intermediates may be formed, transported, and processed further; the final curing in open systems is achieved by temperature and pressure of curing agents. Phenoplast resins include phenols and aldehydes; in the majority of cases, phenol (108952) and formaldehyde (50000) are used. Two types of polycondensation may be distinquished: acid and alkaline. The phenoplasts have applications as lacquer, casting resin, moulding compound, glue, and impregnation for paper and wood; well known resins include urea (57136), melamine (108781), and thiourea (62566) resins. Decomposition of phenoplasts and aminoplasts may occur by heating. The acute toxic effect for oral uptake of phenol is similar to that of percutaneous absorption: asthenia, headache, vertigo, tinnitus, irregular respiration, circulatory failure, coma, and death. Chronic intoxication is very seldom found; symptoms arise from the gastrointestinal tract and central nervous system, and damage to liver and kidney. Formaldehyde may produce bronchitis, dermatitis, rhinitis, oropharyngitis, and conjunctivitis. Phenol sensitization occurs less frequently than formaldehyde sensitization. Resin glues are primary skin irritants and should be handled with gloves. Dusts or fumes should be exhausted from the actual sites of emanation.