StringWriter stw = new StringWriter();
HtmlTextWriter htextw = new HtmlTextWriter(stw);
grdExport.HeaderRow.Style.Add("font-family", "Arial, Helvetica, sans-serif;");
grdExport.HeaderRow.Style.Add("font-size", "8.20px");
grdExport.HeaderRow.Style.Add("color", "#284775");
grdExport.Style.Add("font-family", "Arial, Helvetica, sans-serif;");
grdExport.Style.Add("font-size", "8px");
grdExport.Columns[3].ItemStyle.Width =Unit.Pixel(10);
grdExport.RenderControl(htextw);
Document document = new Document(iTextSharp.text.PageSize.LETTER.Rotate(), 10, 10, 42, 35);
string path = "sample".pdf";
PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(path, FileMode.Create));            
StringReader str = new StringReader(stw.ToString());
iTextSharp.text.html.simpleparser.HTMLWorker htmlworker = new HTMLWorker(document);
htmlworker.Parse(str);
Response.Write(document);
document.Close();