<p>The study to know the effects of lac cultivation (<i>rangeeni</i> strain: <i>katki</i> crop) on the growth, yield attributing and biochemical constituents of pigeonpea, <i>Cajanus cajan</i> (L.) was conducted for two years. For <i>katki</i> (rainy season) crop, the brood lac was inoculated on pigeonpea plants during the mid-July and observations were recorded on biological and productivity linked parameters of lac insect. The initial density of lac insect settlement was 30.70 ± 2.64 insects/ cm² with mortality percentage of 20.72 ± 1.42. The duration of <i>katki</i> crop varied from 107 to 112 days. Growth parameters (plant height, branches per plant), yield characters (pods per plant, seeds per plant, 100 seed weight, grain yield per plant) and biochemical constituents (total chlorophyll content, total sugar, soluble protein and free phenol) were recorded in lac inoculated plants and were compared with un-inoculated plants. There was significant reduction in plant height and number of pods per plant due to lac cultivation, however number of branches per plant and seeds per pod were not significantly different between lac inoculated and un-inoculated plants. Lac cultivation resulted in 16.13 and 16.91 per cent reduction in 100 seed weight and grain yield, respectively. The correlation between scrapped lac yield and grain yield was found to be significantly negative (<i>r</i> = − 0.962). A decrease in total chlorophyll content in leaves (13.48%) and protein content in seeds (22.50%) was observed in lac inoculated plants, however there was an increase in phenols (31.80%) and total sugars (3.11%). Pigeonpea crop was found to be promising and may be utilized as a potential host to develop integrated system for lac cultivation so as to get additional benefits as compared to sole crop.</p>